Apparatus for discharging particulate material from containers

ABSTRACT

This invention relates to improved means for discharging particulate material such as flour or cement from a hopper or like container, particularly those fitted to vehicles for the transport of such material. The hopper is of generally cylindrical construction converging to a reduced vertical cylindrical extension at the bottom forming a well from which the material is discharged. A discharge pipe extends radially outwardly through the wall of the well and an air pipe extends radially through the wall of the well diametrically opposite the discharge pipe. The air pipe has a forward extension of reduced diameter which enters the inlet opening of the discharge pipe and the end of the air pipe around the forward extension is sealed off. The air pipe is axially slidable in a stuffing box so that in its fully extended position it abuts against the end of the discharge pipe preventing discharge of material, whilst in its fully retracted position a space is provided between the ends of both pipes permitting discharge of material which is aerated and blown through the discharge pipe by the air passing through the reduced forward extension of the air pipe.

United States ateat FOREIGN PATENTS [72] Inventor Allan M. Doble Hughesdale, Victoria, Australia A.\.\i.\'!un1 Ijiuminer- Francis J. Bartuska A1mrnc \-Stevens, Davis, Miller & Mosher [73] Assignee Godfrey Engineering (Australia) Pty. Ltd.

Victoria, Australia The hopper is ofgenerally cylindrical construction converg ing to a reduced vertical cylindrical extension at the bottom forming a well from which the material is discharged.

[54] APPARATUS FOR DISCHARGING PARTICULATE MATERIAL FROM CONTAINERS A discharge pipe extends radially outwardly through the wall of the well and an air pipe extends radially through the wall of the well diametrically opposite the discharge pipe. The air pipe has a forward extension of reduced diameter which enters the inlet opening of the discharge pipe and the end of the air pipe around the forward extension is sealed off. The air pipe is axially slidable in a stuffing box so that in its fully extended position it abuts against the end of the discharge pipe 54 3 Hw20%6 M U N 5 H n k H2 Z w u u 2 u 0 m H m w n ..9 S m mm .W n F m m g m m n t :l u H w n .N m m Tm D m m 4 m We S u S m L h i 0 h C 6 U has 2 0 5 55 References Cited preventing discharge of material, whilst in its fully retracted UNITED STATES PATENTS 6/1919 Leonard position a space is provided between the ends of both pipes permitting discharge of material which is aerated and blown 302/25 UX through the discharge pipe by the air passing through the 1,319,193 10/1919 Von Porat PATENTEUuuv 9 mm sum 2 or 2 N I N APPARATUS FOR DISCHARGING PARTICULATE MATERIAL FROM CONTAINERS This invention relates to the discharge of material in powder or granular form from hoppers and the like particularly hoppers or containers fitted to vehicles for the transport of such material, though it is applicable also to fixed hoppers, silos and the like.

In the specification of Australian Pat. No. 215,932, there is disclosed apparatus for the foregoing purpose. This prior apparatus has been extensively used with considerable success and it is the general object of this invention to provide improvements in discharge apparatus of that general kind.

Accordingly the invention provides means for discharging aerated particulate material from a hopper or other container comprising a discharge passage communicating at its inner end with the interior of a lower portion of the container, an axially slidable air pipe disposed parallel to the discharge passage and projecting forwardly into the latter within the container, the discharge end portion at least of said air pipe being substantially smaller in cross-sectional area than the discharge passage, and a valve member projecting outwardly from the air pipe at a position spaced from the inner end of the latter, said valve member being adapted to abut against, and close, the inner end of the discharge passage when the air pipe is disposed in its fully projected position.

Preferably the discharge end portion of the air pipe comprises a reduced forward extension of a main air pipe disposed coaxially with the said discharge passage, said main air pipe having a closed inner end which forms the said valve member.

Preferably the said air pipe, or said reduced extension thereof is disposed eccentrically with respect to the discharge passage.

More particularly the hopper or other container is preferably formed at the bottom with a centrally disposed well having said discharge passage extending laterally outwards therefrom in which case the said air pipe extends laterally through the wall of the well in diametrical opposition to the discharge passage.

The said discharge passage is preferably formed by a discharge pipe, the inner end of which projects into the well so as to be spaced from the wall thereof.

In order that the invention may be more fully understood, representative forms thereof are hereinafter described by way of example with reference to the accompanying drawings in which:

FIG. 1 is a cutaway perspective view of one form of discharge apparatus according to the invention.

FIG. 2 is a view in sectional elevation showing the discharge means incorporated in a container embodying different means for aerating the material therein.

FIG. 3 is a view in cross section taken on the line 3-3 of FIG. 2, and

FIG. 4 is a view similar to FIG. 3, and shows an air discharge pipe of a different cross-sectional shape.

FIG. 1 shows a hopper of conventional shape provided centrally at the top with a filling opening which is normally closed by a cover 11.

A reduced vertical cylindrical extension 12 at the bottom of the hopper is closed at its lower end, and forms a well from which the particulate material, e.g., flour or cement, contained therein is discharged, as hereinafter described, in a fluidized condition.

This material is fluidized by the introduction of air in any suitable manner such as by providing an annular skirt 23 arranged within the upper portion of the convergent lower portion of the hopper, and spaced from the latter to form a narrow intervening space which is open at its lower end.

In order to fluidize the material, air is continuously supplied to the upper part of this intervening space and is discharged downwardly through its open lower end whereby, in addition to permeating the material, it forms an air slide to facilitate movement of the material into the well as more fully described in our said prior specification.

Air is supplied to the said space from an encircling external pipe 16 which is connected by a pipe 18 to an air supply pipe 20 fitted with a regulating valve 22.

A discharge pipe 24 projects radially inwards through the wall of the well 12 and into the latter so that its open inner end is spaced from the wall.

A coaxial air pipe 26 projects inwardly into the well through the diametrically opposite portion of the wall of the latter. This air pipe is axially slidable for which purpose it extends through a stuffing box 28 and its outer end is connected by a flexible hose 30 to a branch 32 from the air supply pipe 20, this branch being provided with a further regulating valve 34.

The air pipe 26 is axially slidable by operation of a hand lever 36.

As so far described, this apparatus is the same as the apparatus described and illustrated in the specification of said prior patent.

For the purpose of the present invention, however, the air pipe 26 is closed at its inner end and is fitted with a reduced axial extension 26a which at all times projects into the open inner end of the discharge pipe 24. Preferably, and as shown, this reduced extension is arranged eccentrically with respect to the pipe 26, whereby it is disposed close to the bottom of the discharge pipe 24.

The extension 26a thus partly obstructs the entrance to the discharge pipe but its reduced size is such as to permit of the free entrance thereto of the fluidized material.

FIG. 2 shows the foregoing discharge means applied to a chamber 10 of somewhat different shape at the bottom and in which aeration of the contained material is effected in another known manner. Thus this container is provided with a false bottom 38 formed of a porous membrane or other porous material, so that air supplied to the space below this false bottom passes uniformly upwardly through it to permeate the powder or other particulate material in the chamber.

When the air pipe 26 is moved inwardly to its full extent, its closed inner end abuts against and closes the entrance to the discharge pipe 24 as shown in FIG. 2, thereby to prevent the discharge of material through the latter.

When, however, the air pipe 26 is retracted from its fully closed position, a gap is formed between its closed end and the open end of the discharge pipe to permit the fluidized material to pass into the latter, and the rate of discharge may be regulated by adjusting the length of this gap, the maximum length of which is equal to the distance between the adjacent inner ends of the discharge pipe 24 and the stuffing box 28 which in the illustrated construction also projects into the well to some extent.

When the air pipe 26 is fully retracted, its extension 260 still projects into the discharge pipe 24 and preferably for a distance approximately equal to or greater than the internal diameter of said extension.

It is to be understood that the extension is not necessarily of circular shape in cross section, as it may be of any other suitable shape such as that shown in FIG. 4.

As compared with said prior apparatus, the improved discharge apparatus herein disclosed has been found to discharge the material at higher speeds while also its operation and adjustment are more readily controlled for the reason that the adjustment of the air discharge pipe 26 is not critical, whereas with the aforesaid prior apparatus, air eddies were produced in the gap between the air pipe and the discharge pipe, and their suppression or adequate control required careful adjustment of the position of the air pipe. With the present invention, therefore, the flow of material is more steady and streamlined. Also, better scavenging of the container is obtained when the container is almost empty, due to the jet pump effect of the air discharged directly into the discharge pipe.

In addition, it is well known in the pneumatic conveyance of materials that it is advantageous to introduce air into the conveyor duct some distance downstream from the point of entry of the material and this is achieved with the present invention without using an additional externally arranged nozzle or nozzles.

Again as the projection of the air pipe extension 26a into the discharge pipe 24 reduces the area through which the fluidized material may enter the latter, it automatically restricts the rate of inflow with the result that the risk of blockage is avoided even when the pipe 26 is retracted to its full extent to discharge material at the maximum rate.

Finally, the location of the discharge end of the extension 26a within the discharge pipe produces a back pressure which ensures that an adequate flow of air to the aerating means is automatically maintained, whereas with our prior apparatus it was found necessary to provide a further regulating valve between the valve 22 and the aerating means to ensure that adequate air was supplied thereto under all conditions of operation.

It has so far been found preferable for the internal area of the air pipe extension 26a to be approximately one quarter of the internal area of the discharge pipe 24 so that when both pipes are circular in cross section the internal diameter of the extension 26a would be about one half of the internal diameter of the discharge pipe 24. Also, when the air pipe 26 is withdrawn to its maximum extent when the length of the gap between it and the discharge pipe may be of the order of one to one and a half times the internal diameter of the pipe 24, it is preferred that the extent to which the extension 26a then projects into the pipe 24 should not be less than one-half of the internal diameter of the latter and not more than six times its said internal diameter.

lt is, however, to be understood that the invention is not limited to such relative dimensions.

lclaim:

1. Means for discharging aerated particulate material from a hopper or other container, comprising a fixed discharge pipe communicating at its inner end with the interior of a lower portion of the container, an axially slidable air pipe disposed in said portion confronting said discharge pipe, means connecting said air pipe to a source of air pressure, and means to axially move said air pipe relative to said lower portion, said air pipe having a first portion of equal diameter to said discharge pipe and a forward extension of reduced diameter extending into said discharge pipe, said air pipe portion serving as a valve member adapted to abut against, and close, the inner end of the discharge pipe when the air pipe is disposed in its fully projected position, said forward extension projecting into said discharge pipe in all positions of said air pipe.

2. Means for discharging aerated particulate material as claimed in claim 1, wherein the forward extension of the air pipe is disposed eccentrically with respect to the discharge pipe.

3. Means for discharging aerated particulate material as claimed in claim 1, wherein the projection of the forward extension of said air pipe into said discharge pipe reduces the area through which fluidized material may enter the latter thereby restricting the rate of inflow thus avoiding blockage even when the air pipe is retracted to its full extent.

4. Means for discharging aerated particulate material as claimed in claim 1, wherein the internal cross-sectional area of the said forward extension of the air pipe is approximately one quarter of the internal cross-sectional area of the discharge P 5. Means for discharging aerated particulate material as claimed in claim 1, wherein both said discharge pipe and said air pipe are circular in cross section and wherein, when the air pipe is withdrawn to its maximum extent, the gap between said air pipe and said discharge pipe is of the order of one to one and a half times the internal diameter of the discharge passage and said forward extension projects into said discharge pipe a distance of not less than one-half the internal diameter of said discharge passage and not more than six times the internal diameter of said discharge passage.

6. Means for discharging aerated particulate material as claimed in claim 1, wherein said lower portion of said contamer IS formed at the bottom with a centrally disposed well having said discharge pipe extending laterally outwards therefrom and said air pipe extending laterally through a wall of the well in diametrical opposition to the discharge pipe.

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1. Means for discharging aerated particulate material from a hopper or other container, comprising a fixed discharge pipe communicating at its inner end with the interior of a lower portion of the container, an axially slidable air pipe disposed in said portion confronting said discharge pipe, means connecting said air pipe to a source of air pressure, and means to axially move said air pipe relative to said lower portion, Said air pipe having a first portion of equal diameter to said discharge pipe and a forward extension of reduced diameter extending into said discharge pipe, said air pipe portion serving as a valve member adapted to abut against, and close, the inner end of the discharge pipe when the air pipe is disposed in its fully projected position, said forward extension projecting into said discharge pipe in all positions of said air pipe.
 2. Means for discharging aerated particulate material as claimed in claim 1, wherein the forward extension of the air pipe is disposed eccentrically with respect to the discharge pipe.
 3. Means for discharging aerated particulate material as claimed in claim 1, wherein the projection of the forward extension of said air pipe into said discharge pipe reduces the area through which fluidized material may enter the latter thereby restricting the rate of inflow thus avoiding blockage even when the air pipe is retracted to its full extent.
 4. Means for discharging aerated particulate material as claimed in claim 1, wherein the internal cross-sectional area of the said forward extension of the air pipe is approximately one quarter of the internal cross-sectional area of the discharge pipe.
 5. Means for discharging aerated particulate material as claimed in claim 1, wherein both said discharge pipe and said air pipe are circular in cross section and wherein, when the air pipe is withdrawn to its maximum extent, the gap between said air pipe and said discharge pipe is of the order of one to one and a half times the internal diameter of the discharge passage and said forward extension projects into said discharge pipe a distance of not less than one-half the internal diameter of said discharge passage and not more than six times the internal diameter of said discharge passage.
 6. Means for discharging aerated particulate material as claimed in claim 1, wherein said lower portion of said container is formed at the bottom with a centrally disposed well having said discharge pipe extending laterally outwards therefrom and said air pipe extending laterally through a wall of the well in diametrical opposition to the discharge pipe. 